Systematics Section / ASPT
Fisher, Amanda E. , Triplett, J.K. , Ho, Chi-Sing , Schiller, Alicia D. , Oltrogge, Kimberly , Schroder, Eric , Kelchner, Scot A. , Clark, Lynn G. .
Paraphyly in the bamboo subtribe Chusqueinae (Poaceae: Bambusoideae): a case of systematic error?
A preliminary parsimony analysis of five chloroplast loci suggests that Chusquea, the world's largest genus of bamboos (ca. 140 described species), is embedded within Neurolepis, a primarily Andean genus comprising 21 described species. Monophyly of each genus is supported by vegetative morphology, in particular the presence of dimorphic multiple buds in Chusquea, and the lack of aerial branching in Neurolepis. Their sister relationship is supported by spikelet morphology and the presence of papillae on the subsidiary cells of the stomatal apparatus. Prior analysis of morphology combined with plastid rpl16 intron sequence data hinted at the possible paraphyly of Neurolepis, and additional sampling and additional sequence data sets appear to strongly support this surprising result. To verify our results, we tested whether the paraphyly of Neurolepis could be an artifact of the phylogenetic analysis. Both Neurolepis and the outgroup taxa have long branches that might influence outgroup rooting when systematic error is present. We used the method of Anderson and Swofford (Mol. Phylogenet. Evol. 33:440-451) to test for long branch attraction and sampling effects in our topology. We also looked for incongruence between data sets, robustness of gene tree topologies to the model of character evolution employed, and model adequacy. Alternative hypothesis testing, in which Neurolepis was constrained to be monophyletic, was performed using the SH test under multiple models. A comparison of these results and their affect on hypotheses of morphological evolution in this clade will be discussed.
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1 - Idaho State University, Department of Biological Sciences, Campus Box 8007, Pocatello, Idaho, 83209, USA
2 - Iowa State University, Department of Ecology, Evolution & Organismal Biology, 253 Bessey Hall, Ames, Iowa, 50011-1020, USA
long branch attraction
Presentation Type: Oral Paper:Papers for Sections
Location: Continental A/Hilton
Date: Tuesday, July 10th, 2007
Time: 8:15 AM